How's this for a delayed response?
I'm afraid I don't have any information on Alexander, as this is the first I've heard of him. It was the names Donald Campbell and Janet Innes which jumped out at me.
Donald and Janet had at least three children: James, Marion, and Georgina. There was also an Ann Campbell living with their family in the 1841 census (by which time Donald had died) but I haven't figured out if she was a sister or a cousin. James lived in Sutherland his whole life; he married Marion Matheson and had three children. One of James's children died in childhood; the other two married relatively late and had no children as far as I know.
Georgina gave birth to an illegitimate son in 1852--my great-great-grandfather, William MacDonald. She subsequently married a widower from Tain named Alexander Reid and moved with him to Glasgow, leaving William behind with his grandmother. She had two sons with Alexander, one of whom died in infancy. After Alexander died she married Michael Kenney, and after that the trail goes cold. I'm still trying to figure out what happened to her and her other son, John James Reid.
I had no idea what happened to Marion until I stumbled upon this post, so thank you for making it! I'm sorry to hear she died so young, both for her sake and because that means there probably aren't many Campbell descendants in Australia who might know things like "who were Donald's parents?" or "how was Ann related to the other Campbells?" I looked up Marion's death record and saw that her daughter Marion died in infancy; did she have any other children?
